Receive the latest breaking updates in your inbox

The Ritz Carlton restaurant staff became suspicious when one of the bombers refused to give his name and provided an invalid room number.

The suicide bombers who blew up two luxury hotels in Jakarta Friday acted suspiciously enough to draw the attention of lobby staffers moments before the deadly blasts.

Three security guards at the JW Marriott confronted one of the bombers who wore backpack on his chest and disregarded their requests for him to stop, Bloomberg reported. The Ritz Carlton bomber sparked suspicion when he provided a non-existent room number at the hotel restaurant.

On Friday morning, the Marriott bomber exited the elevator with a luggage trolley, Alan Orlob, global head of security for Marriott told Bloomberg News. As he walked toward a room where a group of CEOs from the business advisory company, CastleAsia, were meeting, he told two security guards that he had something to deliver to his boss. A third security guard attempted to stop him, but he continued into the meeting room and blew himself up.

At nearly the same time, the Ritz Carlton bomber entered a hotel restaurant for breakfast, indicating to staff that he was staying in room 2701, Orlob said. When the staffer indicated that there was no such room, as there are only 26 floors in the hotel, and asked for the bomber's name, he declined to provide it and offered to pay cash instead. He was seated, ordered a coffee and detonated his bomb.

"What can you do?” Orlob, a former deputy sheriff and U.S. Army special forces soldier, said. “He would have blown anyway. These guys have failsafe devices on the bombs and he would have killed the two security officers and anyone standing in the lobby.”

The double blasts killed a total of 9 people, including the two bombers, and injured 53, disrupting a four-year calm that was beginning to heal the country's reputation as a terrorist hub.

Police found a third, undetonated bomb in Marriott room 1808, and they suspect that the bombers' intent was to detonate that bomb first, sending guests scrambling for the lobby where they would be met with a second blast, a police source told Reuters.

Investigators are looking into how the men got the bombs into the hotels, and are discussing the use of X-ray devices, bomb sniffing dogs, and entry barriers to prevent future attacks.

So far, the men have not been identified, though there's speculation that they belong to the Al-Qaeda linked Jemaah Islamiyah group, who had carried out similar attacks in Jakarta and on the island of Bali.